1. Field of the Invention
The present invention relates to a semiconductor device and method of manufacturing the same, more particularly to a semiconductor device having a semiconductor chip in a package with wiring patterns of microstrip structure and terminators, and a method of manufacturing such device.
2. Description of the Related Art
In case of a high speed LSIs (Large Scale Integrated Circuit), a signal line requires to be connected to a terminator since signal reflection should be restrained to prevent operation from malfunction caused by a waveform distortion. Because of this, there have proposed terminators incorporated in a package which houses an LSI chip to make it possible in high density mounting, instead of externally mounting those on the package.
Japanese Laid-Open Patent Application No. Hei5-206202 has proposed such a semiconductor device. FIG. 8(a) is a plan view showing the semiconductor device proposed in the application, and FIG. 8(b) is a sectional view indicative of the arrows C-C' shown in FIG. 8 (a) Referring to FIGS. 8(a) and 8(b), a metal lead 64 is formed on a lower surface of an insulation film 61 made up of polyimide resin having an opening portion 61a so that the end portion of metal lead 64 is extruded to the opening portion 61a. A resistor 66 used for a terminator comprised of either a thin-film or thick-film is formed on the upper surface of insulation film 61. One end of the resistor 66 is connected to the metal lead 64 via a through hole 67 formed on the insulation film 61. In addition, a bump 62a formed on a semiconductor chip 62 is connected to the end portion of metal lead 64, mounting the semiconductor chip 62 on the opening portion 61a.
It is noted that the value of resistor 66 is a value to be matched with the characteristic impedance of metal lead 64 which becomes a transmission path. The through hole 67 is formed extremely close to the opening portion 61a to desirably restrain reflection in the transmission path.
Accordingly, with the terminator mounted on the package, a simple and high density mounting can be achieved, and with use of a micro process for forming either thin or thick film to be readily made the terminator, resistance accuracy can be enhanced.
In such case of the semiconductor device described above, the reflection restraint effected by the terminator may be small since the metal lead 64 as a transmission path of the package is not a structure so that a characteristic impedance variation such as a microstrip path becomes small.
The external connection also has limitation around the peripheral portion package. Besides, the end portion of terminator has open, therefore, electrical connections for such grounding potential and source potential of the terminator should be placed around the peripheral portion of package when mounting the semiconductor device on a printed circuit board. Thus, reductions of mounting area and mounting man-hour cannot be made sufficiently. Particularly, in case of increasing the number of connecting pins, there arises difficulty of mounting the device on a printed circuit board due to the connecting congestion around the peripheral portion of package.
In addition, with necessity for forming the terminator on the insulation film 61, use of a thin-film causes high cost since its manufacturing method is limited to the vapor deposition. In case of using a thick-film method (or printing method), there arises drawback that variation of resistance value becomes large. In also case of using the thin-film method and electrodeposition method (or plating method), the yield is generally as much as -10 to +10% per a desirable resistance value, while in case of using the printing method, the yield is over -20 to +20%.